Microclimate effects on plant morphology

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

منو

" Microclimate effects on plant morphology "
M. H. Memar S. E. Taylor

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112527
Doc. No	:	TLpq303866682
Main Entry	:	M. H. Memar
	:	S. E. Taylor
Title & Author	:	Microclimate effects on plant morphology\ M. H. MemarS. E. Taylor
College	:	Iowa State University
Date	:	1990
student score	:	1990
Degree	:	Ph.D.
Page No	:	621
Abstract	:	Leaf thickness is important to production and to efficient plant use of water. Leaf size and thickness often vary in response to changes in the light environment. Recent studies have indicated that thicker leaves may have higher photosynthetic rates (under high light) without increased transpiration. Leaf thickening therefore may have important effects on the plant adapting to its environment. The objectives of this study were to determine the phenology and extent of morphological changes during leaf acclimation to light, and to investigate the factors that influence optimal leaf thickness in a given light environment. Soybean (Glycine max L.) and velvetleaf (Abutilon theophrasti Medic.) were grown in and transferred between high and low light environments after leaf expansion (10th leaf) appeared complete. Leaf thickness, dimensions and specific leaf weight (SLW) were measured on single leaves or leaflets. Total internal leaf cell surface area (AR) and cell volume (VR) per unit leaf surface area were measured on 1-mum thick leaf cross sections, fixed in resin, using a stereological technique. In both species high and low light grown leaves had highest and lowest thickness, respectively, with transferred leaves exhibiting intermediate. The anatomical parameters SLW, VR and AR followed trends similar to leaf thickness. Leaf thickening was rapid during early stages of leaf development, and the potential for thickening continued beyond the period of leaf length and breadth expansion. Fully expanded leaves developed in shade were capable of thickening if light levels increased. Leaves developed in high light exhibited a time lag between areal expansion and thickening. This may prevent potentially wasteful investment in biomass should leaves be shaded late in development. A cost-benefit method was used to evaluate the effect of leaf thickness on carbon balance. For these species optimum leaf thickness in a given light environment may be defined as the thickness that maximizes carbon gain at highest possible profit per unit of leaf material invested. Under a high light environment, greatest profit was realized for thick leaves and low stomatal resistance. Profitability was more sensitive to stomate resistance than to leaf thickness under low light.
Subject	:	Agronomy
	:	Biological sciences
	:	morphology